It's All Relative

Accelerating at 4g for a day gets to about 1% the speed of light.

That got me to wondering if I should be accounting for time dilation.

I found a table showing the X axis as a percentage of the speed of light labeled in tenths with 1.0 at the far right.

That had a sharp curve for the time dilation in the Y axis and 10x dilation at the upper right corner...

"Holy BLEEP!" I says.

Then I realized.

1.0 is 100%...

There's hardly any time dilation at 1% the speed of light.

According to that graph, even 90% the speed of light is around 2x dilation.

It's not near the issue science fiction led me to think it was with anything close to a plausibly realistic engine.

Unrealistic engines almost always come with a faster than light drive that takes the worries about relativity off the table.

Edit to add:

That graph I referenced should not be taken to mean that there's "only" 10x time dilation at the speed of light.  That line is near vertical there and isn't quite at c.  The closer you get to c, the more dilation you get, forever.